THE CANADIAN ENTOMO'LOGIST 201 



suggest a close affinity with B. flavicomis Br. Until the male is known, how- 

 ever, and until the reproduction. habit is estabHshed, there is not sufficient justifi- 

 cation for linking the genus wnth that of Erncstia. In X. labis the chaetotaxy 

 of the scutellum differs from that of all the known species of Brnestia. 



Pyraustoiiiyia pcnitalis Coq. exhibits the same peculiar scutellum chaeto- 

 taxy found in X. labis, and is probably not congeneric with Brnestia. 



In so far as is known, all the members of the genus Brnestia have the 

 habit of depositing living maggots in the path of their host. 



Interrelations of the Nearctic Species 

 The nearctic species of the genus Brnestia differ from one another 

 chiefly in the structure of the male genitalia — most of the species are in fact in- 

 separable without reference to these organs. Arranging them in a series ac- 

 cording to the degree of specialization of the genitalia, one can therefore gain 

 some idea as to their immediate ancestry. The most generalized condition of 

 the genitalia is found in B. flavicomis Br.. B. nigrocornca sp. n.. B. chalybea 

 Coq.. and B. frontalis sp. n., where the base of the inner forceps has developed 

 no median keel-like projection. In arcuata sp. n.. johnsoni sp. n.. nigropalpis 

 sp. n.. and incisa sp. n. there is a well-developed keel-like projection. More 

 highly specialized again are B. aldrichi Tn. and B. longicarina sp. n. in which the 

 keel-like projection has become longer than in any other known nearctic species. 

 In B. platycarina sp. n. one margin of the carina has become flattened. In 

 sulcocarina sp. n. the same margin has become grooved. In bicarina sp. n. the 

 groove in the carina has developed to such an extent that a splitting has oc- 



^ ^ [> nlL.c> ^ <i> ir 



irontilii arcuicavma. mgii>piljws-alcli'i-<J)i / / 1 1 lon.gica.pina., saltiicttpiritt . iica.pin.au anv^eluc 



cured so that there are two keel-like projections instead of one. Finally, in 

 B. anipelus Walk., and in B. fissicarina sp- n.. the two keel-like projections have 

 become reduced into a pair of J<nob-like structures. From these facts the 

 group would appear to be monophyletic. With the evolution of the keel-Hke 

 projection in mind, it is possible to test the validitv of the genus Fansta proposed 

 for the reception of forms having the sides of the face abnormally wide. In 

 the type species B. ncmorum Meig.. the keel-like structure is in the generalized 

 condition found in B. flavicomis Br.. B. frontalis sp. n., B. nigrocornca sp. n.. 

 B. ritdis Fall, and B. radicum Fab. In the nearctic species genalis Coq.. on the 

 otljer hand, there is a well-developed unsplit median keel-like projection as in 

 B. arcuata. It would seem, therefore, that Fansta is not a natural genus, as 

 the species are less closely related to one another than to species in the genus 

 Brnestia.- -An explanation that suggests itself is that in the evolution of the 

 Brnestia group a widening of the sides of the face has taken place twice; first 

 when the genitalia were still generalized, and secondly when a keel-like process 

 had been developed. Such a relationship can be expressed by retaining 



